Investigation of the Roles of NCN and HNO Reactions on NOx Formation in Combustion Processes

NCN自由基和HNO在燃烧过程中作为氮氧化物（NOx）形成的中间体发挥重要作用。用于开发和优化污染物减少策略的详细而复杂的反应机理依赖于许多基本气相反应的精确速率常数参数化。虽然已经做了大量的工作来开发NOx的形成submechanisms，在最近几年中，它已经变得很清楚，NCN自由基的途径，以避免NO的形成是不正确的实施在models.During本项目的第一个资金期间，直接速率常数测量的一些最重要的NCN反应可以进行的第一次。为了组装一个完整的NCN高温机制，将继续对选定的双分子NCN反应进行类似的激波管研究。使用激光吸收技术，包括新开发的中红外检测系统，将测量许多物质（NCN、OH、CN、HCN、CH、N）的浓度-时间曲线。此外，将进行额外的实验来澄清NCN的生成焓和高温吸收截面的一些有争议的值。所有数据的组合结果在一个纯粹的实验为基础的NCN子机制，将对更复杂的反应系统的实验进行验证，并实施到现代火焰机制。火焰模拟将显示，如果首要的研究目标，即一个可靠的模型，在火焰中的氮氧化物的形成，将得到满足。 就HNO而言，在第一个供资期内，首次可以在冲击波后探测到这种难以测量的物质。频率调制检测系统的进一步优化将使得能够测量包括HNO + O2、H和OH的所选HNO反应的速率常数。到目前为止，HNO动力学的高温数据是罕见的，很大程度上分散，因此这些测量提供了一个改进的HNO火焰模型的基础上，为燃料-NO的形成和燃料-N-转换。

NCN radicals and HNO play important roles as intermediates in the formation of nitrogen oxides (NOx) in combustion processes. The detailed and complex reaction mechanisms used to develop and optimize pollutant reduction strategies rely on accurate rate constant parametrizations for many elementary gas phase reactions. Although much work has been done to develop NOx formation submechanisms, in recent years it has become clear that the NCN radical pathway to prompt-NO formation is not properly implemented in the models.During the first funding period of this project, direct rate constant measurements of some of the most important NCN reactions could be performed for the first time. Similar shock tube investigations of selected bimolecular NCN reactions will be continued in order to assemble a complete NCN high temperature mechanism. Using laser absorption techniques, including a newly developed mid-IR detection system, concentration-time profiles of many species (NCN, OH, CN, HCN, CH, N) will be measured. Moreover, additional experiments will be performed to clarify the somewhat disputed values of the enthalpy of formation and the high temperature absorption cross section of NCN. The combination of all data result in a purely experimentally based NCN submechanism that will be validated against experiments of more complex reaction systems and implemented into modern flame mechanisms. Flame simulations will show if the overarching research goal, i.e. a reliable modeling of NOx formation in flames, will be met. In terms of HNO, during the first funding period this difficult to measure species could be detected behind shock waves for the first time. Further optimization of the frequency modulation detection system will enable rate constant measurements of selected HNO reactions including HNO + O2, H and OH. So far, high temperature data on HNO kinetics are rare and largely scattered; hence these measurements provide the basis for an improved HNO flame model for both prompt-NO formation and fuel-N-conversion.